Fouling-resistant, water-remediation apparatus, system, and method

ABSTRACT

An apparatus, system, and method isolate anodic ion generation from precipitation and flocculation with target metal ions. Hyper-turbulent flow conditions in an ion generator confine reaction and flocculation to a precipitator downstream. Shear forces in a laminar boundary layer at a cylindrical anode separate anodic (sacrificial) ions from target ions effectively eliminating agglomeration in the bulk flow traveling in a hyper-turbulent flow regime through the generator. A precipitator downstream provides a dwell time for reaction between ions and initial agglomeration of reaction products therefrom. A controller, limiting electrical current through the generator (of anodic ions), optimizes operation without overdriving current, while virtually eliminating fouling of the anode. The system resists co-habitation of ion generation and precipitation and their distinct, respective flow regimes of hyper-turbulent and laminar flow. Physically separated spaces and unique conditions isolate processes, eliminating conventional problems.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/313,392, filed Jun. 24, 2014, which claims the benefit of U.S.Provisional Application Ser. No. 61/838,464 filed Jun. 24, 2013, both ofwhich are hereby incorporated by reference.

BACKGROUND Field of the Invention

This invention relates to treatment of waste water and, moreparticularly, to novel systems and methods for heavy metals removal froma waste water stream.

Background Art

Prior art systems exist for various types of waste water treatment. Forexample, recycling waste water from sewage systems in cities is classicand well established. Moreover, production water from petroleumproduction and coal-bed methane production is also well established.

Typically, removal of heavy metals in particular is accomplished in avat or tank dedicated to an electrochemical, water treatment process. Inthis process, conventional systems focus on a balance between problems.For example, fouling occurs as a result of flocculation and precipitantaccumulation on electrodes and other reactive surfaces. Engineersbalance between throughput or flow rate of waste water treated andefficiency measured with respect to the amount of surface area availableon reaction plates, and so forth.

Typically, maintenance is excessive in many designs. In fact, much ofthe prior art is dedicated to the issue of maintenance of systemsparticularly with regard to cleaning off reaction plates (electrodes).Various deposits may accumulate as a direct result of chemical reactionsin the waste water treated and the electrical activity near theelectrode.

As a practical matter, maintenance, and particularly cleaning ofelectrode plates, is at the center of much of the prior art literatureand accepted as a given, or requirement. It is simply inescapable, dueto the nature of the processes occurring in the reactor tank. Forexample, an electrochemical reaction occurs at each of two electrodes.Typically, a sacrificial anode or simply an anode will donate positivecurrent (draw electrons) in order to generate certain ions.

At an opposite, cathodic, electrode, electrons are donated to ions, suchas ions of hydrogen. This generates hydrogen gas as a byproduct of thefreeing up of ions for reaction in the tank. The release of hydrogen andformation of hydrogen ions into hydrogen gas are a direct result ofbalancing the electrochemical reaction. Stated another way, the balancedhalf reaction of the hydrogen necessarily involves acceptance ofelectrons and formation of the hydrogen gas.

Another aspect of the prior art is the attention to certain electricalschemes created for the purpose of interference with, reduction of, orreversal of the plating out or coating of undesirable materials overelectrodes. Coating of electrodes tends to interfere with theireffectiveness, system efficiency, and so forth. As a practical matter,reversing polarity between electrodes is a common approach to reversingthe coating process.

Nevertheless, it has been found by the inventors that such coatingprocesses are not necessarily reversible. In fact, they tend to resistreversal, and require effectively undercutting the coating in order toremove it. In other words, the coating often becomes an effectivedielectric or insulation barring free flow of electrons in the reactionsat the electrodes.

In other prior art systems, the generation of hydrogen bubbles, andtheir natural tendency to rise, are relied upon as an agitation sourceto scrub or remove coatings from surfaces. As a practical matter, due toboundary layer theory of fluids, these actually tend to simply disruptthe formation process, and are largely ineffective, for actuallyremoving deposits that have already been deposited on an electrode.

In short, myriad schemes for manipulating polarities, cycle times,frequencies, and the like exist in the prior art. Regardless of attemptsto optimize surface areas, optimize resistance to coating by insulatingreaction products, minimize fouling by flocculating compositions, andthe like have largely been effective only in slowing the process ofcoating, and not effectively eliminating extensive maintenanceoperations and costs. Thus, what is needed is a system that operateswith a minimum of maintenance. In fact, it would be a great advance inthe art to provide an electrochemical reaction system that iseffectively self-cleaning, resistant against coating of electrodes, orboth. It would be a further advance in the art to remove the commonpractice of de-rating systems according to their actual capacitycompared to their engineered capacity.

Moreover, their capacity over time degrades far below their initialcapacity. For example, the frequent and necessary process of maintenanceor disassembly for cleaning is so ubiquitous that systems are de-ratedso that they may be properly sized by being over-designed. Thiseffectively amounts to reducing the expectations of performance in placeto comport with reality. Between actual disassembly for cleaning atperiodic times, the intervening performance degradation must be properlyaccommodated.

Thus, it would be a great advance in the art to provide a system thathad a consistent, high fraction of available operational time. It wouldbe a further advance to effectively eliminate routine cleaning ifpossible.

If possible, it would be a great advance in the art to relegatemaintenance to replacement of consumed sacrificial anodes, in duecourse, rather than cleaning those or other electrodes. It would beanother advance in the art to develop a process for design of a systemthat operates within a set of operational parameter values thateffectively preclude cleaning as a requirement.

It would be another advance in the art to develop a process for design,and a system so designed, that result in uniform sacrificial donation ofions from a surface of a sacrificial anode.

It would be an advance to provide a consistent measure of efficiencyover time and predictability of replacement.

It would be another advance in the art to create a system, and a methodfor designing systems, that would be responsive to variations in theincoming waste water treated. For example, different petroleousformations have inherent geological differences, resulting in differentchemistries for the surrounding water or production water. Thus, wastewater treatment may be subject to large variations in the constitutionof heavy metals and other constituents such as dissolved solids,salinity, and the like. Accordingly, it would be an advance in the artto provide a system and a method for designing systems that can beresponsive to changes in the constitution of incoming waste waterwithout altering the reduced maintenance, operational efficiency, and soforth.

Another advance in the art would be to provide an increased efficiencyof precipitation of heavy metal compositions separated out from thewaste water stream. In this regard, it would be a further advance in theart to provide a system for designing a predictable performance ofprecipitation of the extracted materials. This may be expressed as aprecipitation efficiency of a system.

BRIEF SUMMARY OF THE INVENTION

An alternative to electro-coagulation isolates ion generation andprecipitation of target ions from one another. For example, each isrelegated to a subsystem optimized for accomplishing its own objective(e.g., ionization and precipitation, respectively) to the virtualexclusion of others. Performance of all functions is improved,electrical efficiency is improved, power use is reduced, heating oftreated fluids is reduced or eliminated, and separation of target ions(e.g., heavy metals) is improved.

Conventional pitting, channeling, variations in surface texture, and thelike that typically result from coating are eliminated. Stated anotherway, coating is eliminated, so the effective degradation of asacrificial anode is a direct function of uniform reduction ofthickness. In the case of a cylindrical sacrificial anode, the radiusuniformly decreases smoothly along the entire length and about theentire circumference during operation.

In one method of reclamation of a flow of waste water, a system of pumpscontrol head, which thus controls pressure, velocity, mass flow rate,and the turbulence that will exist in conduits carrying the fluid. Plugflow is enforced within at least the ion generator. Along the entirelength thereof, plug flow exists, meaning that the Reynolds number iswell into the turbulent region, well beyond any critical zone in thetransition region. Typically this involves Reynolds numbers much greaterthan five thousand, typically greater than ten thousand, and often onthe order of twenty thousand to thirty thousand.

Plug flow represents a hyper-turbulent condition at a Reynolds numberwell above the critical zone range. The typical critical zone of thetransition region for the Reynolds number is between about two thousandand five thousand. Below a Reynolds number of about one thousand is verystably laminar flow. That is, flows at Reynolds number values below onethousand are well into the laminar range and not susceptible to changeswith disturbance. Similarly, flows having a Reynolds number greater thanfive thousand are turbulent. At a Reynolds number greater than tenthousand, a flow is well into the turbulent region, and incapable ofdropping back to a laminar flow absent a radical change in operatingparameters, such as the velocity, diameter, significant length, or thelike.

Thus, plug flow is maintained along the entire operating length of ananode in a cell of an ion generator in accordance with the invention.Plug flow indicates that a velocity profile is substantially all at asingle value of velocity, except in a very thin layer near a wall, suchas from about one percent to about ten percent of the overall availablediameter or available radius.

Similarly, the flow is unidirectional throughout an ion generator. Thebulk flow direction is axial, not twisting, turning, reversing,crossing, or the like in other directions.

A system in accordance with the invention may provide for recirculation.The system may recirculate certain output water that has already beencleaned, in order to control the concentration of incoming water to beremediated. The circulation pump may be controlled by a control valvewhich effectively trims the head (pressure, typically measured in termsof a height at some standard acceleration, such as the value of gravity)that results from the circulation pump.

A main pump delivering fluid to be remediated will typically notovercome a recirculation pump through a control valve. The recirculationpump, when throttled back with the control valve, cannot overcome ordominate the flow from the main drive pump. Thus, the flow from bothpumps may be combined in order to pass into an ion generator at acondition of concentration (constitution of water with its constituentions and in total dissolved solids) that can be effectively handled bythe system.

An ion generator may include a conduit in which a hyper-turbulent, plugflow operates in a unidirectional mode, progressing axially along theconduit. Effectively no radial component nor back component to bulkvelocity exists. Near the wall thereof, the hydrodynamic boundary layerwill provide some slight amount of recirculation as understood inboundary layer theory. However, this is not even a significant portionof the volumetric flow rate (cubic feet per minute or liters perminute).

In one embodiment, stagnation points are not permitted along a conduitin an ion generator. The flow is preferably directed through across-sectional area that has little or no change in area, dimension,shape, or the like along the length thereof.

Necessarily, certain guides may be required in order to position ananode along a central axis of a conduit. These may occasion a slightamount of interference with the cross-sectional area, but will add toturbulence. They will not tend to make the flow any more nearly laminar,nor generate stagnation eddies. By stagnation eddy is meant a regionwhere flow may actually come to a stop or reverse in the axial directionor main direction of flow.

The Reynolds number is greater than the critical zone value at allsignificant points within the conduit. This is typically from about twoto about six times the value of Reynolds number in the critical zone ofthe transition region's end (maximum value). Likewise, there may be asingle transition area at an entrance to the conduit, wherein fluid maycome in perpendicularly or from a conduit of another diameter in orderto feed into a particular cell of an ion generator. Similarly, a singletransition at the exit will typically be downstream of the sacrificialanode. That anode may be configured as a cylindrical rod passing axiallyalong the center of a conduit carrying the fluid to be remediated. Therod furnishes ions as the sacrificial anode.

The hydrodynamic boundary layer near any walls adjacent to thehyper-turbulent flow provides mechanical shear selected to overcome weakchemical bond forces, and specifically Van der Waal's forces. Only ionicbonds may survive the turbulence and the laminar shear (at a solidboundary) extant throughout the lumen of a conduit in the generator.

Tripping devices, or trippers may be used in order to trip flows inregions where the possibility of reduced Reynolds number may exist.Textures on surfaces, ridges, dams, disruptions, or changes in directionat highly localized locations and the like may trip a laminar boundarylayer, turbulent boundary layer, or both in order to maintain thorough,actual turbulence.

Calculation and design of a system may require assessment of hydraulicdiameter of a conduit, selection of the velocity, investigation andaccommodation of fluid properties, minimizing a hydrodynamic boundarylayer, maintaining a constant axial cross-sectional area of flow, andthe like. It may benefit from maintaining all flow parallel to an anodesurface, such that net ion migration or diffusion exists onlyperpendicular to the anode surface. This results in an effectiveelectrodynamic machining process actually carrying ions away from thecontact surface of an anode in the conduit of a cell of the iongenerator.

The hydrodynamic boundary layer is minimized by the hyper turbulence ofthe flow. Meanwhile, the diffusion boundary layer is minimized in thatit is coincident with the entire laminar portion of the hydrodynamicboundary layer, and then may extend into a micro eddy portion of thetransition region to turbulent flow. For example, transition fromlaminar flow to turbulent flow at a solid boundary will typicallyinvolve micro eddies that have a circulation component while stillmoving axially along the path of the boundary.

Thus, diffusion is minimized in the direction toward the anodethroughout the diffusion boundary layer. The flow of current, drawingelectrons from any metals in the flow will result in a plethora of ions(a comparatively high concentration) near the surface of the anode. Bymatching the mass transport rate of convective processes carrying ionsout of the diffusion boundary layer and into the bulk plug flow of theconduit will assure that no effective precipitation can occur in the iongenerator.

Rather, sacrificial metal ions are driven into the bulk flow by a flux,effectively approaching saturation with respect to the maximum currentoutput by a current source driving the ion generator. Meanwhile, aradial flow of ions is matched with an axial flow of fluid with thoroughand immediate mixing of ions into the bulk flow. Thus, only in a coreregion near the anode is any diffusion gradient extant, and not actuallydistinguishable, as a practical matter. That is, the hydrodynamic anddiffusion boundary layers are simply too thin to include a significantportion of the flow. The constant, radial, cross-sectional area providesa diffusion per unit length that is substantially constant and thusrepresents a linear curve along the entire length of a cell of the iongenerator.

Moreover, a unidirectional, axial, mechanical load on the anode resultsfrom centering the anode in a seat of a holder or guide engineered forthe purpose near the exit end of the cell. Meanwhile, another guidepositions the upstream end of the anode near the flow entrance withinthe conduit. The conduit itself, meanwhile, operates as a cathode.

There is no need nor benefit to alternating the current flow or theroles of the anode and cathode. There is no benefit to swappingpolarity. A system in accordance with the invention precludes coatingout any significant precipitants on the anode. There is no need to tryminimizing that coating, nor trying to reverse that coating, byacidifying the fluid in order to scavenge hydroxides from the fluid.

In one embodiment of an apparatus and method in accordance with theinvention, no manipulation of the polarity, modulation, reversal, changeof magnitude, or the like is required in order to avoid precipitation inthe ion generator. Rather, isolation of precipitation is physical. Theion generator has a separate device, containment, and flow path from aprecipitation reactor. They occupy no coincident physical space.Moreover, the hydrodynamic, hyper-turbulent flow regime within the iongenerator precludes precipitation and precludes any agglomeration ofprecipitants. The hydrodynamic shear precludes any agglomeration of ionsunder weak forces, such as Van der Waal's forces.

Moreover, no acid need be added to the water to be treated upstream fromthe ion generator. No hydroxide ion scavenging is necessary. Rather, theavailability of hydroxide ions need not be manipulated nor controlled.Hydrodynamic effects simply assert control over the agglomerationprocess, thus effectively precluding them from the ion generator.

Stated another way, the hyper-turbulent flow and the comparatively highrate of shear in the hydrodynamic boundary layer will precludeagglomeration of precipitants, and even tend to reverse any occasional,statistically random, chance precipitation of constituents. This isbecause the availability of hydroxide ions, heavy metal ions, andsacrificial ions, is so ubiquitous, yet extra charge is not available.This system does not run excess currents similar to electro-coagulationsystems.

Thus, a system in accordance with the invention isolates precipitationphysically, isolates ion generation from precipitation reactions byhydrodynamic shear, and does not require acid or other hydroxidescavengers in order to manipulate the availability of hydroxide ions tometal ions. Downstream from the ion generator, the addition offlocculating polymers, adjustments of pH in order to optimize theavailability of reactants for precipitation in the precipitationreactor, and so forth may be considered and included.

The reactor operates in the laminar flow regime, and may even becompletely quiescent. Stagnation is not necessarily general. A certainamount of mixing may be beneficial to provide availability of ions toone another for reactions. Nevertheless, the laminar flows that have aReynolds number value less than half that of the critical zone (e.g.,less than half of about two thousand) may be considered to be wellwithin the laminar flow regime.

One may analyze water, and create a report. One may analyze ionconcentrations and types based on the report of inductively coupledplasma (ICP), chromatography, or other testing systems. Accordingly, onemay determine by calculation of electrons required for ionization acurrent limit. For example, the numbered ions times the charge per unitis the current required to remove all those ions at their charges. Thesum of all species of ions provides the total charge.

That amount of charge per unit volume, and the volumetric flow rate,will control the amperage required. Amperage is the current flow ofelectrons needed per unit of time to match the reaction of the number ofions passing per unit of time through the precipitation reactor portionof a system. Electrical energy need not be devoted to overcomingresistance of coatings. Very little energy is wasted as heat.

The amperage is a function of ion generation, and is largely independentfrom any resistance. Typically, the only resistance to be overcome isthat inherent in thermodynamic processes of ionization. The electricalenergy need only be sufficient to break bonds of metals with electrons,in order to create metal ions. There is no need to provide excessiveadditional current. Energy is needed to the extent that thermodynamicsrequires the minimum of losses required by its first and second laws fora process to occur.

Meanwhile, a system does not need the amount of electrical energy commonin the prior art (e.g., Electrocoagulation or EC). Prior art systemsneed to overcome the electrical resistance of dielectric coatings ofprecipitants on electrodes, such as a sacrificial anode. Moreover,electrical energy is required for electrophoresis of ions through thethickened prior art fluids. Here, mechanical mixing provides all thediffusion required outside the boundary layers.

A system in accordance with the invention may optimize a curve ofoperation representing electrical conductivity (proportional to ionconcentration) as a function of current in a separate ion generator. Themass transport (transfer) limit may be calculated initially from theprinciples of heat and mass transport as well as chemical diffusionthrough boundary layers of fluids. A definition of a mass transportlimit and an electric current limitation will establish an envelopewithin which the operation of curve will be found. It is typicallydesirable to improve the operational curve toward the limits of theenvelope established by the current limit and the mass transport limit.

The system may also track independent variables, which include current,flow, and chemical constitution. Typically, current, flow, and, to alesser extent, the constitution of the fluid may be manipulated byindividual controls. The constitution may be manipulated by diluting anincoming fluid stream to be remediated. On the other hand, flow andcurrent are typically controlled almost directly. As a practical matter,current may be controlled by a feedback control loop on a currentgenerator between the cathode and anode.

The system may measure and track the dependent variables such aselectrical conductivity, temperature, and pH within the flow of a fluid.The system may accordingly adjust the operation of the curve within themass transport limitation and the current limitation of the system.Sensors may measure conductivity variations as current is increased andreduced. Accordingly, process controllers may evaluate the comparison ofslopes, and determine whether the benefits of increased current willprovide sufficient increase in ionization of anode metal. The system maytest the slope operating of the curve at various conditions and therebylimit the processes to avoid operating in a fouling region in which toomuch current applied to an anode results in coating out of precipitantson the anode.

In certain embodiments of apparatus and methods in accordance with theinvention, an ion generator may be fed by a current source to treat aflow of incoming water. In certain embodiments, a precipitation reactormay be connected to receive the output of the ion generator. As apractical matter, it has been found effective to separate the iongenerator from a precipitation reactor in order that the processes ofprecipitation, flocculation, and the like be completely isolated fromthe generation of ions.

In certain embodiments, it has been found most effective to maintain ahigh-velocity, well established, turbulent flow throughout the iongenerator. Thus, the electrochemical reaction driven by the currentsource is effective to generate large (comparatively) masses of metalions from a sacrificial anode into a very turbulent flow (Reynoldsnumber well into the turbulent region, and consistently well away fromany laminar-to-turbulent transition).

It has also been found effective to rely on a channel or lumen that isannular in shape. The sacrificial anode is best made a cylinder axiallyaligned in a cylindrical tube acting as the cathode. Thus, thesacrificial anode is completely surrounded by treated fluid. The highvelocity, high turbulence, and generalized mixing of plug flow resultsin a rapid carriage of ions into the bulk of the stream. This alsocauses a minimization of hydrodynamic boundary layer, diffusion boundarylayer, and any tendency to coat out the anode.

A flocculant polymer may be injected into the flow between the iongenerator and the precipitation reactor. This provides several benefits.For example, the precipitation reactor is separate from the iongenerator. The flocculant source provides a source of flocculatingpolymer. Thus, the precipitation reaction and flocculation ofprecipitants cannot be effective, and cannot overcome the turbulent flowand boundary layer shear within the ion generator.

Moreover, in contrast to prior art systems, separating the precipitationreactor from the ion generator provides for a flow in the precipitationreactor that may range from quiescent to laminar flow. Inelectro-coagulation systems, ion generation and precipitation reactionscommonly compete with one another in the same tank. Thus, prior artsystems would damage the flocculation process if turbulence wereallowed. Meanwhile, such quiescence or laminar flow in the presence ofan anode will increase hydrodynamic boundary layers, and the diffusionboundary layer, both resulting in higher rates of coating out andfouling.

In a system and method in accordance with the invention, ion generationtakes place in an environment optimizing the rate of ion creation, andminimizing the processes or effects contributing to coating. Meanwhile,the precipitation reactor is optimized specifically for flocculation.Turbulence is effectively eliminated by maintaining the flows wellwithin Reynolds numbers below turbulent transition. Moreover, in certainembodiments, the Reynolds number is often double the Reynolds number atthe high end of the critical zone of the transition region or greater.

The Reynolds number in the precipitation reactor is often in the rangeof half the beginning critical zone of the transition Reynolds number.This may be a value of one thousand or less. Thus, each of the iongenerator and precipitation reactor may be optimized to maximize theeffectiveness of the process to which it is dedicated.

In order to provide low Reynolds numbers (e.g., slow to quiescent flows)with some modicum of mixing sufficient to promote precipitationreactions, the precipitation reactor may include elements such asbaffles, channel obstructions, flow path variations, and the like.Gates, and the like may maintain laminar bulk flows while stillproviding the exposure required to create molecular availability oratomic availability for reactions.

Typically, the actual separation of flocculated precipitants may beconducted in a clarification unit. Typical clarification units includeinduced gas flotation (IGF), dissolved air flotation (DAF), settlingtanks or settlers, or the like. Typically, such systems rely on time,gravitational separation of heavy materials from lighter materials, andso forth. Typically, the reference in such systems is to “scraping” orseparating off the lighter materials appearing near the top of aprocessing tank, while augering out sediments from the bottom of suchtanks. A water outlet therebetween removes the water separated from thecontaminants.

A post processing unit may be added. For example, a distillationprocess, reverse osmosis, activated carbon filter, or the like may beplaced in line with the output from a clarification unit. The postprocessing unit may thus return the treated waste water to a conditionsuitable for subsequent use. Such subsequent uses may include, forexample, irrigation, drinking water, process water, and so forth.

In some embodiments, a certain amount of the water output from theclarification unit may be recycled in a bypass or circulation loop. Thecirculation loop may be driven by a circulation pump restricted by acontrol valve in order to control incoming concentration by providing acertain amount of make up water into the ion generator. An alternativeis to use fresh water or a separate source of clean water to dilute theconcentration of a particular incoming waste water stream.

In the petroleum production industry, commonly called the oil and gasindustry, water may simply be reinjected into an injection well drilledfor the purpose. Thus, the production water removed from the earth as abyproduct of petroleous production may be reinjected into another drywell, below underground aquifers

Notwithstanding the fact that the water is reinjected, it is desirablethat the water not contact aquifers. Nevertheless, the purificationrequirements are such that the possibility of eventual contact withaquifers is still kept in mind. For example, heavy metals are removedpermanently.

As a practical matter, the injection wells are typically drilled to adepth consistent with petroleum production. In the oil and gas industry,the removal of heavy metals and compounds of heavy metals also serves toprevent fouling of the injection well itself, the bores as well as theformation into which the water is injected. Otherwise, over time,fouling will eventually block access and destroy the utility of aninjection well.

Similarly, water used for formation fracturing (commonly referring to asfracking) also has environmental limitations as well as foulingconcerns. Thus, removal of heavy metals and their compounds reducesfouling and increases the longevity of a particular well and aformation.

In another system and method in accordance with the invention, a controlscheme has been developed by which the system may be operated, designed,trimmed, and monitored. In certain embodiments, a current limit isestablished, as well as a mass transfer limit. These correspond,respectively to the electrochemical reaction rates available at thesurface of a sacrificial anode and the diffusion and mass transferprocesses due to hydrodynamic and diffusion boundary layers within thesystem.

Accordingly, it has been found that a system may be controlled tooptimize capital expenditure or balance capital expenditure on systemsagainst the operating costs, such as power costs. Likewise, maintenancecosts may be so balanced or optimized. Fouling may be effectivelyeliminated by controlling a system within parametric values inaccordance with the apparatus and method.

The operating envelope may be bounded by the current limit and masstransfer (mass transport) limit. These govern the relationship of ionconcentration (as reflected in the electric conductivity) as a functionof the current input for a sacrificial anode.

By maintaining values of operational parameters within the envelopedefined by the current limit and mass transfer limit, an operationallimit on performance may be established. For example, by tracking asuitable dependent variable, such as electrical conductivity of thewaste water stream, the effectiveness of reactions along the path ofthat stream may be tracked and controlled.

In this example, an initial period of ion generation may effectivelydegenerate to a linear curve that may be relied upon consistently.Meanwhile, the decay of electrical conductivity as the precipitation andflocculation processes proceed may also be measured, characterized, andparameterized to provide suitable predictions of performance.

In fact, depending on whether the incoming stream is effectively cleanwater with heavy metals in it, brine containing heavy metals, or somecombination containing only metals, only salts, or the like, certainoperational parameters may be established, and an operating envelope maybe defined. These operating envelopes have been established byexperiment and demonstrated to be operative.

In certain embodiments, a quick release system for replacement of anodeshas been developed to provide rapid replacement of individual cells.Taking a cell offline, minimizes downtime for replacement of anodes. Theonly operational degradation of that anode is consumption. Current maybe maintained at a constant value regardless.

In order to break an emulsion or coalesce small liquid droplets in adilute dispersion, an alternate process may pass the emulsion or dilutedispersion through the EcoReactor system. Since aluminum is not requiredin the process, the current between electrodes may be turned down so lowthe potential of the electric field (voltage) is low enough that noaluminum is oxidized into ions.

Alternatively, the process may use an anode and cathode of material morenoble than aluminum (e.g., stainless steel, gold, etc.) with highervoltage. A less noble metal may also be used if a more noble metal iselectroplated or sputtered on it to prevent corrosion or oxidation.

Such a device acts as a coalescer (EcoCoalescer). As far as processoperation, it operates very similarly. The device does not remove heavymetals, and has significantly less onerous maintenance requirements(e.g., no anodes to replace). Operation costs are on the order of 70%less as well.

Potential candidate emulsions or dilute dispersions are heavy or lightphase effluent from a liquid/liquid separator (e.g., centrifugal,gravity, etc.), drilling mud, used motor oil, used lube oil, dilutesilica in water mixtures, effluent from a flotation or settlingoperation, etc.

When the emulsion or dispersion passes into the coalescer, itexperiences an electric field gradient. The electric field gradientcauses electrophoretic movement of the droplets and distortion of thedroplets. This movement, distortion, or both will cause the small,dilute droplets to coalesce more quickly due to closer proximity orfavorable reduction, distortion, or both of the zeta potential. Thismethod of coalescence works with any droplet or particle where thedroplet or particle has an unbalanced electric charge (e.g., oil, clay,etc.) or with any droplet or particle where an unbalanced electriccharge may be induced (e.g., oil, silica, etc.).

It is important in the design and operation of the coalescer that theflow be such that the residence time of the fluid be sufficient forcoalescence to occur, but not so long as to waste power. The flow alsoneeds to be quiescent enough not to break up any coalesced droplets butnot so quiescent as to require undue capital costs for equipment size.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the present invention will become more fullyapparent from the following description and appended claims, taken inconjunction with the accompanying drawings. Understanding that thesedrawings depict only typical embodiments of the invention and are,therefore, not to be considered limiting of its scope, the inventionwill be described with additional specificity and detail through use ofthe accompanying drawings in which:

FIG. 1 is a schematic block diagram of an apparatus and process inaccordance with the invention;

FIG. 2 is a schematic diagram of the chain of reactions occurring in thesystem of FIG. 1;

FIG. 3 is a schematic diagram of the flow within the annulus of an iongenerator in accordance with the invention, indicating velocityprofiles, concentration profiles, and geometric relationships;

FIG. 4 is a schematic diagram of the ionic reactions at the electrodes,anode and cathode, of an ion generator in accordance with the invention;

FIG. 5 is a graph indicating the curves of current limit, mass transferlimit, and the electrical conductivity performance curve of a system andmethod in accordance with the invention;

FIG. 6 is a schematic block diagram of a process in accordance with theinvention for setting up, evaluating, and controlling the performance ofa system along the performance curve of FIG. 5;

FIG. 7 is a graph showing the electrical conductivity, reflecting ionicconcentrations within a waste water treatment stream, as a function ofdistance through the system, including passage through the ion generatorand precipitation reactor of FIG. 1;

FIG. 8 is a chart showing a least squares fit of data in a log-logformat showing the correlation of actual experimental data to thecalculated predictions of a system in accordance with the invention;

FIG. 9 is a chart showing a least squares fit of data in a log-logformat showing the correlation of actual experimental data to thecalculated predictions of a system in accordance with the invention,according to another series of tests; and

FIG. 10 is a partial, side-elevation, cross-sectional view of oneembodiment of a quick-change-out cell system for the ion generator inaccordance with the invention, including its sacrificial anode, whichmust be replaced periodically.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It will be readily understood that the components of the presentinvention, as generally described and illustrated in the drawingsherein, could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theembodiments of the system and method of the present invention, asrepresented in the drawings, is not intended to limit the scope of theinvention, as claimed, but is merely representative of variousembodiments of the invention. The illustrated embodiments of theinvention will be best understood by reference to the drawings, whereinlike parts are designated by like numerals throughout.

Referring to FIG. 1, a system 10 in accordance with the invention mayinclude an ion generator 12 responsible for generating ions of a metalanode. The anode referred to as a sacrificial anode, delivers ions intoa solution of waste water to be remediated.

Waste water may arise in a variety of industrial circumstances. Tailwater from mining, production water from petroleous production,production water from coal-bed methane production, industrial processwaste water, irrigation tail water, city sewer systems and surfacedrainage, and the like may all give rise to water containingcontaminants. Certain biological contaminants are handled byconventional mechanisms. In accordance with the invention, a principalcontaminant is heavy metals.

A system 10 in accordance with the invention may include other elements(not shown) responsible for handling volatile organic compounds (VOCs),other organic materials, biological matter, or the like. Meanwhile,salinity may be another issue to be addressed by additional mechanismsor ignored, depending on final disposition such as Re-use versusRe-injection. In the illustrated embodiment, the principal concern isheavy metals that are difficult to remove from water streams. Thedifficulty is related partly to the chemistry of those metals, andpartly to the trace amounts in which they exist. Efficiently processingsuch constituents out of a waste water stream may be problematic, andhas historically been so.

Thus, a system 10 in accordance with the invention may be augmented byadditional components responsible for managing VOCs, organic compounds,salts, biological compounds, and the like. Alternately, some may bepermitted to remain.

Downstream from the ion generator 12 may be located a precipitationreactor 14. The precipitation reactor 14 is responsible foragglomerating various compounds made up of sacrificed metal ions fromthe ion generator, along with hydroxide ions derived from the wateritself, and other heavy metal ions. In general, the precipitationreactor 14 may include flocculation by addition of suitable compoundsdiscussed hereinbelow (e.g., polymers).

A precipitation reactor 14 differs from an ion generator 12 in asignificant manner. In contradistinction to prior art systems, such as,for example, electro coagulation (EC) systems, whether open or closed asto containment of the treated fluids, the ionization process is isolatedto the ion generator 12. The precipitation process is isolated to theprecipitation reactor 14, for all practical purposes.

Ionization, reaction, and the like as chemical processes, are inherentlystatistical in nature. Thus, at any given moment, any particularchemical atom or composition may enter into a reaction with another.Nevertheless, as a statistical probability, such processes typicallyoccur at an appreciable, significant, or measurable rate only undercertain conditions. Thus, the ion generator 12 is specifically designedto provide conditions of highly turbulent flow (well above the criticalzone of the transition Reynolds number range).

In contrast, the precipitation reactor 14 is maintained at a quiescentor at most stably laminar flow (e.g., a Reynolds number of much lessthan the initiation of transition to turbulence, and typically even onthe order of half that value).

The ion generator 12 is designed, described, defined, and operated toprovide minimal residence time. One reason this is so is that the iongenerator 12 is driven electrically, as a function of flow rather thandepending upon or balancing other processes present. For example, theion generator 12 is driven at a high velocity, very high Reynoldsnumber, in a highly turbulent plug flow. This ensures a minimal boundarylayer at all surfaces, and in both hydrodynamic and diffusion boundarylayers.

In contrast, the precipitation reactor 14 may include baffles, weirs,dams, obstructions, gates, serpentine paths, or the like. These mayprovide a certain amount of mixing at very low Reynolds numbers (wellbelow values of two thousand, and frequently less than half that value)in order to assure laminar flow, agglomeration of molecules andassociations of ions by “weak forces” that might otherwise be disruptedby any effective turbulence in the flow. This supports flocculation,development of gels and polymeric reactions, absorption of watermolecules into flocculating polymers, and association of large groups ofions including metallic ions from the ion generator 12 and theconstituent heavy metals, and so forth.

Thus, the ion generator 12 need not be designed to tolerate nor fosterthe weak forces, such as Van der Waal's forces. In direct contrast, theprecipitation reactor 14 by its well-laminarized to quiescent flowexactly fosters flocculation, agglomeration, chemical reaction,precipitation and so forth.

In certain embodiments, a clarification unit 16 may be a settling tankthat simply provides space and time for materials to separate in aquiescent environment. Typically, sediments representing heavyprecipitates may be augured out of the bottom portion of such a unit 16while lighter compositions and mixtures may be “skimmed” from the upperreaches thereof.

A clarification unit 16 may be any of several suitable types. Forexample, an induced gas flotation system (IGF) may foster agglomeratingreactions of various ions that will include (e.g., scavenge) the heavymetals ions desired to be removed from the waste water. To that end, anIGF system, or a dissolved air flotation system (DAF) may operatesimilarly.

For example, these systems may foster flocculation and flotation ofcertain compositions, resulting in a froth or gel that may be separated,skimmed, or “scraped” from near the surface of a tank of a clarificationunit 16. By the same token, smaller particles that are not involved inflocculation, and thus have not entrained air, or trapped air or otherlighter species, may simply drift downward to the bottom of such a tank,becoming sediment. Various types of scrapers may operate near the top ofsuch a tank in order to remove lighter compounds and mixtures.Meanwhile, augers and the like may remove heavy sediments settled out atthe bottom of the clarification unit 16.

A post processing unit 18 may provide additional steps in remediating aflow. Typically, post processing units 18 may include desalinization,reverse osmosis, and other types of purification processes. Suchprocesses executed by post processing units 18, which may be included asone or more individual process units 18, are typically directed topreparing a remediated stream for its specific use.

For example, reinjection of production water from petroleous productiondoes not require removing salt. Thus, brines are often suitable forreinjection. Nevertheless, if water is being prepared for irrigation,culinary purposes, or the like, then desalinization and other processesmay be included in a post processing unit 18.

Any type of post processing 18, including those referenced in the priorart as final “polishing steps” or processes may be included. Theoperating specifications will tell what is required as the output of asystem 10 in accordance with the invention. Nevertheless, as a practicalmatter, a system 10 may be used in combination with a variety of otherprior art systems, in order to accomplish the functions of those priorart systems. Thus, the existence or utility of such a prior art systemdoes not obviate the utility and special functionality of a system 10 inaccordance with the invention.

A major distinction between an apparatus and method in accordance withthe invention and prior art systems for removing heavy metals from wastewater treatment streams is the isolation of the ion generator 12 inorder to maximize ion generation. In contradistinction to prior artsystems, there is not a direct balancing, in a single vessel, of the iongeneration function of the ion generator 12 and the precipitationreaction processes of the precipitation reactor 14. Rather, each ofthese is designed, sized, and optimized for its own function, within itsown environment, and its own respective, isolated, system 12, 14.

In general, waste water 20 or a feed 20 may be passed into a pump 22 forraising the pressure in a downstream line 46. Typically, the pump 22 maybe augmented by a bypass line 24 or recirculation line 24. Herein, onemay speak of the line 20, 24, or the flow 20, 24, since is each isconnected to the other.

In general, a bypass flow 24 or bypass line 24 may be driven by a pump26. Typically, a control valve 28 may be set as a resistance against thefree flow in the line 24. Accordingly, the pump 26 may actually be setto pump against the resistance of valve 28. A resulting flow is added tothe incoming raw water 20 introduced into the ion generator 12 as theflow 30.

The flow 30 may simply be the flow 20 directed into the ion generator12. Nevertheless, in certain situations, concentration may be desired tobe controlled. The bypass line 24 or recirculation line 24 may providerecirculation of part of the output of the clarification unit 16. Thus,the precise concentration may be provided for one of several reasons.

Briefly, some of those reasons may simply be the capacity of the iongenerator 12, the capacity of the precipitation unit 14, or the capacityof the clarification unit 16. If concentrations vary, which they oftenwill between various production units and over time, then increases mayotherwise overwhelm or overrun portions 12, 14, 16, of the system 10.Instead, the flow 20 may simply be diluted by recirculatingcomparatively clean (e.g., cleaned) water in the recirculation line 24.

Likewise, the ion generator 12 in accordance with the invention isconstructed in a modular fashion such that additional cells 90 may beadded to the ion generator 12. They may simply be taken on and off linewithin a battery of such cells 90 in the ion generator 12. Thus, thecapacity of the ion generator 12 may be modular even while online, inorder to accommodate rapid variations, need for dilutions, or the likewhile still maintaining a specified throughput or treatment of anincoming raw waste water stream 20.

The ion generator 12 may be engaged by cells 90 in a modular fashion tomaintain a specific throughput rate for a precipitation reactor 14.Rather than tying the capacities of the precipitation reactor 14 and theion generator 12 together, each may be adjusted to operate according tothe parameters or the constitution of the incoming water 20. They mayadjust independently from one another, in order to maintain each withinits preferred operating envelope at optimal performance.

The line 34 may include a pH adjuster 31 to add an acid or a base intothe line 34. For example, acidity may affect reaction rates, solubilityof the heavy metal precipitates, or both. Thus, the addition of acid orbase in the output 34 of the ion generator 12 may be accomplished,resulting in an adjusted pH in the line 36 entering the precipitationreactor 14.

By the same token, and for similar reasons, a flocculant source 32 mayinject certain polymers into the line 34, thus adding to the line 36additional polymeric materials effective for IGF, DAF, and so forth.

The output 34 from the ion generator will eventually, after augmentationby the pH adjuster 31 flocculant source 32 pass into the precipitationreactor 14. The entire quantity or content of the line 34 will typicallypass into the precipitation reactor 14.

The reactor output 38 includes all the content introduced by the output34 from the ion generator 12, as well as any constituents from the pHadjuster 31 and the flocculant source 32, as modified by reactions andflocculation within the precipitation reactor 14. Therefore, theclarification unit 16 may include not only an output 39 of the cleanedwater stream, but an output 41 of the lighter materials removed from thetop of the unit 16, and the heavy sediments as an output 42 from thebottom of the unit 16. Thus, after the post processing unit 18 may havefurther processed the output 39, the final output 40 is the flow of“cleaned” water output from the system 10, and suitable for thedesignated use.

A current source 50 is electrically connected to the ion generator 12.Each cell within the ion generator 12 receives current through the line54 (positive charge, in an electrical engineering convention), andelectrons in the electrical line 52 (physicist, electron point of view).As a practical matter, the current source 50 may be configured in avariety of forms. Typically, sensors within the ion generator 12, orelsewhere may detect voltage drops or other variations in voltage as aresult of changes of conditions.

For example, a sacrificial anode may decay with time, increasingdistance to the cathode, thus altering the required voltage required tomaintain current. Nevertheless, by whatever control mechanism isimplemented, of which several are available, the current source 50generates a current set and maintained at an operational level.

In general, the current source 50 is designed to provide a flow ofelectrons sufficient to liberate from a sacrificial anode, the metallicions, according to the charge of each. Thus, for example, in oneembodiment, an aluminum rod may act as the sacrificial anode.Accordingly, three electrons are required to liberate an aluminum ionfrom the matrix of the metal, or the close association with itsmetallic, atomic neighbors. The current source 50 may be designed toprovide that amount of electrical charge (remove that many electrons)required to generate the required number of ions (e.g., aluminum ions).The number of ions released is the number required to support theeventual precipitation of the requisite number of incoming heavy metalions. The current and sacrificial ions balance the reaction constitutingthe incoming flow 20. Both types exit the ion generator 12, then reactin the precipitation reactor 14.

Referring to FIG. 2, while continuing to refer generally to FIGS. 1through 10, a process 60 represents a chemical reaction as a chain 60 ofindividual, intermediate, chemical reactions. In the illustratedembodiment, the various interactions are statistical in nature. Forexample, an aluminum ion 65 may leave a sacrificial anode 92 and beresident in an aqueous solution. On the other hand, statistically,periodically, certain of those ions may actually re-embed in the anode92 or combined with other atoms. Nevertheless, in the main, on astatistically calculable basis, the various illustrated processes willtake place at calculable rates.

For example, a continuous ion-generation process 62 constitutes theupper portion of the process 60 of FIG. 2. This generation process 62occurs within the ion generator 12. The current provided by the currentsource 50 into the anode 92 introduces ions into the source water 30 iongenerator 12.

The precipitation reaction process 64 represents a series of reactionsoccurring in the precipitation reactor 14. In contradistinction to priorart systems (e.g., EC systems), manipulation of the acidity, or the pHin general, need not be reckoned before the output 34 of the iongenerator 12. The acidic nature of certain waters 20 introduced into anyreclamation system may tend to maintain, fortify, reduce, inhibit, orotherwise interfere with the processes in the precipitation reactor 14.According to convention, acids may be introduced to lower the pH inprior art systems. Specifically, acid may resist scaling or coating ofanodes 92 in the ion generator 12. Prior art systems do not isolate anion generator 12, but maintain some type of combined reaction system.Thus, in order to reduce coating of an anode 92 with insulatingprecipitants, acid may be introduced, thus reducing the pH, acidifyingthe water 30, and scavenging free hydroxide ions 63 within the system10.

In the illustrated embodiment, a particular metal, such as aluminum, maybe introduced as an ion 65 in a solution of water molecules 67. Byincreasing the availability 66 of the aluminum ion 65 in the water 67, areaction 68 may be initiated. In the illustrated embodiment, an aluminumion 65 may combine with a hydroxide ion 63 derived from the water 67.This leaves a free hydrogen ion 69 in solution.

Meanwhile, the aluminum hydroxide ion 70 becoming available 72 toadditional water molecules 71 undergoes a reaction 74 in which thealuminum hydroxide ion 75 now contains multiple hydroxide ions with thealuminum ion 65.

The reaction 74 leaves another free hydrogen atom 76. Meanwhile,additional availability 78 of aluminum ions 77 results in a reaction 80that continues to add hydroxyl groups or ions to a compound 81 or ion81. However, in the illustrated embodiment, additional ions 77 may react80 with the aluminum hydroxide 75 to create larger compounds 81 ofaluminum and hydroxides.

Ultimately, the availability 82 of other metal ions 83, such as heavymetal ions 83 results in a reaction 84 by the metal ion 83 with thecompound 81 or ion 81. The result is the compound 85. At this point, onemay question just how strong each individual bond is as the hydroxideions, aluminum ions, other metal ions, and so forth continue toagglomerate. The settling of such compounds 85 will be driven, to acertain extent, by their density as sediments. However, ongoingreactions 86 continue to make larger compounds 87, held together byweaker and weaker forces.

As a practical matter, the early reaction 68 is largely ionic in nature.Thus, the compound 70 of aluminum hydroxide, although still ionic innature and unbalanced in charge, is maintained by a comparatively large,ionic force. However, the continued precipitation of the compound 81,and more so the compound 85, results in much lower strength bonds.Ultimately, the long chains of the end compounds 87 may actually be“bonded” more by Van der Waal's forces. Thus, a system 10 in accordancewith the invention recognizes the dichotomy in requirements for maximumgeneration of ions 65 versus maximum precipitation. Countervailingprinciples control clean ionization into hyper-turbulent flows, versusthe limited amount of disruption to which a large compound 87 may besubjected during reaction and growth.

Referring to FIG. 3, an individual cell 90 within an ion generator 12may define the line 89 of radial symmetry. In the illustratedembodiment, a radius 91, in general, may be defined as a distance fromthe center line 89. In the illustrated embodiment, an anode 92 may beconfigured as a rod 92 or a cylinder 92 of consistent length, and havinga surface 93 that stands electrically opposite to a surface 95 of acathode 94. The cathode 94 is electrically isolated from the anode 92(at least as for direct current exchange). Thus, the surface 93 of theanode 92 and the surface 95 of the cathode 94 will pass current throughthe intervening fluid within the lumen 96 or annulus 96 of the cell 90.

Typically, a radius 97 represents the inside radius 97 of a tube 94 thatacts as a cathode 94. Here, a cylindrical geometry, or aright-circular-cylindrical geometry, defines each cell 90. Accordingly,an anode 92, and specifically its outer surface 93 establishes with theinner surface 95 of a cathode 94 at a radius 97 the annular space 96 inwhich the fluid 30 will flow. Thus, a lumen 96 or annulus 96 is definedby those radii 97, 111 between the surface 93 and the surface 95. Theydefine the lumen 96 or annulus 96 of the system 10, and particularlyeach cell 90 of the ion generator 12 within the system 10.

Typically, a hydrodynamic boundary layer 98 will be created near asurface 93. According to boundary layer theory, a molecule of a liquidis, nevertheless, stationary at a stationary wall or other interference.The thickness 99 of a hydrodynamic boundary layer 98 will be establishedby the fluid properties of any fluid flowing through the lumen 96.

A diffusion boundary layer 100 will also be established, but typicallyextends to a location different from the hydrodynamic boundary layer104. In the illustrated embodiment, a thickness 107 of the diffusionboundary layer 106 will identify exactly how far chemical diffusion willextend, or how far a concentration gradient of an ion 76 will persist.

Typically, a diffusion boundary layer 106 may have a thickness 107dictated partially by hydrodynamics, and partially by the chemicalconcentration of materials. For example, a convection component tends toprovide mixing in certain regions nearer the bulk center. By contrast,other regions near solid surfaces 95 tend to be dominated by simple,straightforward diffusion of species. In this case, the aluminum ion 65is being released at highest concentration at the anode 92.

Typically, one may define a diffusion boundary layer 106 as includingthe hydrodynamic boundary layer 104 but going further, into a bufferzone 108. The buffer zone 108 may be thought of as a region 108 oftransition in which micro eddies or small-scale turbulence providesadditional convection between a laminar region 98, and the somewhatcirculating, convecting region 102.

The thickness 109 near the cathode 94 need not be the same size as thethickness 103 of the buffer zone 102. Stated another way, each of thezones 108 and 102 is a buffer zone 108, 102, respectively. Yet, each isaffected by the diffusion of its species, including metal ions at theanode 92, and hydrogen ions at the cathode 94.

Typically, a velocity 110 of the bulk flow 130 results in a bulk plugflow 130. For example, a velocity 110 across virtually the entireexpanse of the lumen 96 results in a very flat profile 112.

The flow of a remediated fluid in a cell 90 will typically be a bulkplug flow 130 through an annulus 96 or lumen 96 defined by a radius 97and the radius 111 of the right, circular cylinder that is thesacrificial anode 92. Typically, the velocity 110 of the fluid withinthe lumen 96 generates a velocity profile 112 that spans from the radius111 at a wall face 93 to the radius 97 at the face 95 on the wall 94that forms the cathode 94.

Note that these polarities need not change in the apparatus 10 inaccordance with the invention. Instead, hyper-turbulence preventsflocculation and resists precipitation. The diffusion boundary layer 100extends a comparatively short distance 101 from the face 93 of the anode92. Thus, the boundaries 93, 125, define the diffusion boundary layer100. Similarly, the boundaries 93, 123 establish the hydrodynamicboundary layer 98 between the face 93 and the boundary 123.

Similarly, at the opposite electrode 94, where the wall 94 of a tubeoperates as a cathode 94, the hydrodynamic boundary layer 104 may have adistinct thickness 105. Likewise, the diffusion boundary layer 106 mayhave its own distinct thickness 107. The fact that hydrogen is beingreconstituted at the cathode 94, while ions 65 are leaving the anode 92,with ions 113 being generated in the flow 130 will dramatically affectthe response, and consequent diffusion layers 100, 106.

In either case, a buffer zone 102, 108 may be thought of as a region102, 108 of thickness 103, 109, respectively, wherein the hydrodynamicboundary layer 98, 104 is effectively absent, yet the fully involvedturbulence may not yet be present. A laminar flow 122 will exist withineach of the boundary layers 98, 104. Typically, the concentration 114 ofhydrogen ions is reflected in the profile 116 extending a distance 115from the face 95 of the cathode 94. Meanwhile, the aluminumconcentration 120 may be reflected in a profile 118 of concentrationwithin the lumen 96.

Thus, in general, a hydrodynamic profile 112 reflects the variation invelocity 110 within the bulk flow 130 or which becomes bulk plug flow130 within a lumen 96. Meanwhile, the laminar boundary layers 98, 104reflect the dramatic variation in velocity radially across a region 98,104.

The buffer layers 124 proximate either surface 93, 95 each represent atransition in which ions are eventually diffused to have a uniformconcentration 120 reflected in the flat profile 118, similar to the flatprofile 110 of a fully developed velocity. Similarly, near the cathode94, within some distance 115 may be a concentration 114 of hydrogen ions116.

The regions 98, 102, 104, 106 are thus defined by the boundaries 93,123, 125, 95, 127, 128. Meanwhile, the buffer layers 102, 109 aredefined by their adjacent boundaries 123, 125, and 127, 128,respectively.

Typically, the distances 100, 107 are comparatively small, on the orderof less than ten percent, and often less than one percent of the overallradius 97 across the lumen 96. Thus, the profiles 112, 116, 118 developcomparatively quickly (e.g., close to solid objects 92, 94).

One reason for the existence of the upper zones 103, 108, is the natureof the distinction between laminar flow 122 and bulk, turbulent, plugflow 130. The regions 102, 108 involve turbulent eddies 124 intransition. Meanwhile, the turbulent eddies 124 represent the transitionbetween the laminar flow 122 within the regions 98, 104. The bulk plugflow 130 of the system 10 reflects the bulk turbulence 126 or large,turbulent circulations with no net motion except axial flow.

In contradistinction to prior art electro coagulation (EC) systems andprocesses, a system 10 in accordance with the invention relies on theion generator 12 maintaining plug flow. Plug flow is so absolutelydominated by turbulence throughout that the hydrodynamic boundary layers98, 104 represent an insignificant fraction of the overall flow 130 inthe lumen 96. This causes the flat velocity profile 112 in which thevelocity 110 throughout the lumen 96 may be assumed to be the maximumvelocity 110, to the exclusion of the laminar flow 122 existing in thehydrodynamic boundary layers 98, 104.

The result of plug flow 130 in the lumen 96 of the cells 90 in the iongenerator 12 is that the micro turbulence 124 in the buffer region 108effectively sweeps clear all ions generated at the surface 93 of thesacrificial anode 92. They are carried through the diffusion boundarylayer 100. In fact, the actual diffusion process actually occurs almostexclusively within the laminar hydrodynamic boundary layer 98. In thebuffer region 102, the convection of micro turbulence 124 rapidly mixesall constituents, thus bringing the concentration 120 of the sacrificialions 65 (e.g., aluminum 65, in the illustrated example) up to the levelof the bulk profile 118 thereof as illustrated.

This bulk plug flow 130 is maintained pervasively across substantiallythe entire radius 97 of the annulus 96 or lumen 96. It is also typicallymaintained throughout the entire length of each cell 90, from inlet tooutlet thereof, particularly the length of the anode 92.

This sustained, persistent, pervasive bulk plug flow 130 cannot beachieved in plate types of systems as known in the prior art.Stagnation, back eddies, dead spaces, wide disparity in velocityprofile, and the like, are not permitting of this flow. Moreover,geometries preclude such uniformity.

In contradistinction to other prior art attempts at agitation,“turbulence,” or other periodic or location-specific turbulence, plugflow turbulence is a direct consequence of maintaining specificconditions at a comparatively very high rate of flow. This means a veryhigh Reynolds number (where Reynolds number is density multiplied byvelocity and a significant length, such as a diameter, hydraulicdiameter, or the like, all divided by the viscosity of a fluid) atvalues well into the turbulent region.

Flow near the critical zone of the transition region does not qualify,and will not develop bulk plug flow 130. Thus, whereas the word“turbulence” or “agitation” may be tossed about in prior art, it isclear that such systems as described in prior art references simply donot maintain, cannot maintain, do not suggest, and do not rely on norbenefit from bulk plug flow 130 driven by hyper-turbulence. Typically,in a system 10 in accordance with the invention, Reynolds numbers aremaintained above values of five thousand, and typically at values ofmore than ten thousand. Thus, in a system 10 in accordance with theinvention, Reynolds numbers on the order of twenty to thirty thousand,or more are typical. Thus, this is a full order of magnitude larger thanthe initial value of Reynolds number in the critical zone of thetransition region, which starts at about two thousand. At that point,laminar flow begins to be left behind and transition begins. Typically,turbulence is fully developed beyond the critical zone at a Reynoldsnumber of about five thousand. Here, Reynolds numbers of many times thatvalue assure bulk plug flow 130.

The ultimate effect of bulk plug flow 130 in the lumen 96, is areduction, virtually to the point of eradication, of any effectivecoating of a cathode 94. Precipitation and inward, radial diffusion ofions 65 from the sacrificial anode 92 by any reactants or precipitantssimply has no mechanism. The ionic reactions of metals of any type(sacrificial or heavy metals to be removed) from the incoming waterstream 20 is resisted by the flood of ion 65 and paucity of electrons.Hence, the ion generator 12 is maintained under hydrodynamic,electrical, and chemical conditions to assure that it is substantiallyexclusively an ion generator 12. This occurs to the exclusion ofprecipitation reactions. They are reserved for the precipitation reactor14. Any pretreatment requirements, acidification, or other prophylacticsto forestall, slow, or retard precipitation reactions do not occur hereas in other prior art systems that do not maintain flows within theseReynolds number ranges.

The order of magnitude of the thickness 99 of the hydrodynamic boundarylayer 98 may be of the order of magnitude of the buffer layer 102. Thus,the incursion of precipitants is effectively prohibited. The laminarflow 122 is still vigorous with high shear stress, but is thinned downby the bulk plug flow 130. Thus, the opportunity for any statisticallysignificant diffusion in a reverse direction by precipitants toward theface 93 of the anode 92 has been virtually eradicated. Accordingly,coating out of precipitants on the sacrificial anode 92, is effectivelyprecluded at any significant quantity or with any significantpersistence.

Thus, scrubbing, although effectively present, by the vigorous flow 130in the lumen 96, need not even be relied upon. Rather, the reversediffusion of chemical species toward the anode 92, as it donates itsentire surface 93 in ions, simply does not brook any coating out ofprecipitants on electrodes 92, 94. Moreover, the high power densities,the net current driven (electrons received) by the current source 50into the anode 92, weights the reaction, or the ionic formation processin favor of driving aluminum ions 65 from the anode 92 into the bulkplug flow 130.

Coating (which depends on quiescence, or laggard, laminar flows andstagnation) simply is not permitted at any measurable or calculablerate. As a practical matter the mass transport and electrochemicalbalance in the region 98 is so dominating and so matched to the abilityof the bulk plug flow 130 to carry away the ions, that no species ofheavy metals in the bulk flow 130 can migrate to the surface 93 at anyappreciable rate.

Ions near the electrodes 92 are immediately treated as the ions leavingthe anode 92, themselves losing, not gaining, electrons. Thus, there iseffectively no point at which a precipitated heavy metal ion can land.Hence, in experiments operated by Applicants, the pitting common toelectrodes in conventional electro coagulation systems was completelyabsent. A precisely, electrodynamically machined, outer surface 93persisted at all radii 111 of the anode 92, from new installation, tocomplete decimation. Thus, a system 10 in accordance with the inventionprovides electrostatic machining of the sacrificial anode 92, asprecisely and effectively as electrodynamically machining (EDM) in themanufacturing industry.

An apparatus and method in accordance with the invention rely on thebulk plug flow 130 as a flow regime that is so hyper-turbulent that itvirtually precludes any precipitation reaction within the ion generator12. For example, (e.g., EC) prior art systems typically rely on a tankof some configuration in which generation of ions from a sacrificialanode occurs in the same continuous and contiguous medium as theprecipitation and coagulation reactions. Large molecules or ions aremade up of multiple metal ions and hydroxide ions. Isolation of the iongeneration, as created in the ion generator 12, from the precipitationreactor 14 and its precipitation reaction, is impossible in typicalprior art approaches.

In an apparatus and method in accordance with the invention, theincoming flow 30 received by the ion generator 12 does not include anymanipulation of the pH (basic or acidic nature) of the influent water20. Rather than manipulate the pH to make the flow 30 more acid, an iongenerator 12 in accordance with the invention hydrodynamically isolatesheavy metal ions, that are to be removed from the flow 130, from thesacrificial anode 92.

For example, the hydrodynamic boundary layer 98 is so vigorous in itshydrodynamic intensity, that migration of ions of heavy metals from theflow 130 to the anode 92 is effectively eliminated. First, the anode 92is contributing sacrificial ions 65 at the maximum possible rateavailable based on the current source 50. The approach of some randomheavy metal ions may be occasioned due to the fact that the flow 30 doescontain those ions. Accordingly, any metal ions 83 in the liquid in thehydrodynamic boundary layer 98 will be treated by the anode 92 as ifthey were the same as the ions 65. The anode 92 will simply receive anelectron from that metal, and return it into the flow 130 as a metalion.

Moreover, any compound in which a heavy metal may be found in the flow130 might approach the anode 92, but would immediately be subjected tothe electrostatic potential available from the anode 92, ionizing thecompound, and dismembering the ions or atoms from one another. Thus, theelectrostatic potential near the anode 92 tends to drive metal ions intosolution, not precipitate them out. The fact that the diffusion boundarylayer 100 and the hydrodynamic boundary layer 98 are so comparativelythin compared to the overall radius 97 between the anode 92 and thecathode 94, militates against any precipitation and coagulation.

The hyper-turbulence occasioned by the extremely high (comparatively; onthe order of ten to thirty thousand, typically) Reynolds number withinthe flow 130 presents so much shear in the laminar flow 122, as toovercome any Van der Waal's forces that might exist due to any of thereactions 64. That is, the agglomeration of ions by forces weaker thanionic attractions are overcome by the mechanical shear forces existingbetween stream lines in the laminar flow 122 of the hydrodynamicboundary layer 98. Thus, precipitation and flocculation are effectivelyprecluded mechanically and electrically within the ion generator 12.

The cross-sectional area is substantially constant along the entirelength of each cell 90. There is no appreciable change in velocity ordirection along the length thereof. This results in a uniformly severecondition of shear in the hydrodynamic boundary layer 98. Thus, eachcell 90 provides a hydrodynamically isolated ion generator 12 completelyseparated from the precipitation reactor 14 and its processes.Mechanically, the precipitation reactor 14 is a different physicalcontainment structure. However, the very processes of the reactions 64are precluded by the vigor of the boundary layers 98, 100, the high rateof viscous shear therein, and the inability of any agglomeration ofprecipitants to mechanically survive. Thus, the inertial forces asrepresented in the Reynolds number completely dominate, and will reverseif present, any agglomeration due to Van der Waal's forces or othersimilarly weak attraction.

Referring to FIG. 4, reactions 140 are illustrated schematically.Individual reactions 140, or individual instances of the reactions 140include a release 142 of a metal ion 65, shown here as an aluminum ion65 occur at an anode 92. Electrons 144 driven by a power source 50through the lines 52, 54 facilitate the reaction 142, convertingelemental aluminum to aluminum ions 65.

Meanwhile, a migration 146 may be thought of as a reaction 146 inasmuchas the hydrogen ions 69, 76 from the flow or fluid carrier in which ions65, 69, 76 are present may involve several reactions intermediate theanode 92 and the cathode 94. Those reactions result in a certain degreeof electrophoresis. That is, ions 65, 69, 76, will tend to drift ordiffuse, under electrostatic force, through the carrier liquid (e.g.,water). Also, reactions may occur at one location, facilitating releaseof electrons, facilitating other reactions elsewhere. Hydrogen ions 69,76 may or may not originate near the anode 92 or the cathode 94. On theother hand, the ultimate reaction that provides the ions 69, 76 maysimply be the last in a long chain, dependent upon the rapid transfer ofelectrons between various species and solution.

The result is a donation 146 of the hydrogen ions 69, 76 at the cathode94 where electrons are available for facilitating a reaction 148generating hydrogen molecules 147. The equation 143 governs thegeneration 142 or reaction 142 creating aluminum ions 65. Meanwhile, thereaction 149 governs the conversion of hydrogen ions 69, 76 with theelectrons to form hydrogen gas 147 or hydrogen molecules 147 at thecathode 94. This completes the reaction 148 of the equation 149.

The electrons 144 are released to an anode 92. It accepts electrons fromthe elemental aluminum, causing generation of the aluminum ion 65.Meanwhile, the lines 52, 54 carry those electrons to the cathode 94,where they may readily donated to hydrogen ions 69, 76, resulting inneutralization of their charge, and their stabilization in a covalentbond in the hydrogen molecule 147.

Referring to FIG. 5, the mass transfer (transport) limit 158 depends onsuch dimensionless parameters (well defined in the fluid mechanics andthe heat and mass transport technology) as the Nusselt number, thePrandtl number, and the Reynolds number as reported in the heat and masstransport literature. Properties of consequence are densities, fluidviscosities, heat transfer areas, thermal conductivities, specific heatcapacities of materials, and so forth. The correlations between Reynoldsnumber, Prandtl number, Nusselt number, and other similar dimensionlessparameters that may be applicable to the establishing of mass transferlimit 158 on the theoretical basis are not repeated here, but areavailable in any suitable text on heat and mass transport.

The graph 150 is actually one single graph 150 from an entire family ofgraphs 150. For example, this graph 150 illustrates the variation ofelectrical conductivity 154 as a function of current 152 introduced intothe ion generator 12, or a cell 90 thereof.

However, the entire family corresponds to different settings foradditional parameters taken as constants, unvarying throughout thedomain of this instant graph 150. Some of those other parameters willvary, thus moving into a different plane of operation as represented bythe axes 152, 154. Parameters may include, for example, the constitutionof waste water 20 being treated. Another such parameter that is fixedfor the purposes of the graph 150 is the actual volumetric flow rate{dot over (Q)} (Q dot). Others are the material properties andgeometries associated with the Reynolds number, Prandtl number, andNusselt number, and so forth. For example, density, viscosity,significant length, thermal conductivity, specific heat, and the likeare considered non-variant for the chart 150. Variation of one or moreof those parameters may generate a different chart 150, and specificallya different curve 160.

The experiments conducted by Applicant demonstrate the existence of thecurve 160, and the qualitative relationship illustrated in the chart150. In the illustrated embodiment, the curve 160 has a slope 162 ortangent 162 at any and every point. The slope 162 represents the rate ofchange of the curve 160 at the point of tangency. Several tangent points160, 164, 168, 170 are illustrated. Each has significance.

For example, the point 164 represents an optimum 164, or an operationalpoint 164 that balances several competing considerations. Meanwhile, theboundary line 165 defined by the optimum 164 establishes a region 166 ofall electrical current levels greater than that associated with thepoint 164. This region 166 represents a region in which excessive powerusage from the current source 50 will be likely if additional power isdrawn.

Accordingly, in currently constituted embodiments used inexperimentation, a length of a cell, and thus the length of an anode 92and the effective length of an ion generator 12 have been defined. Theannulus 96 between the anode 92 and the cathode 94 or the tube 94surrounding the anode 92 is defined. Meanwhile, a mass flow rate orvolumetric flow rate of fluid based on the Reynolds number has beenestablished at a bulk plug flow 130 for the regime.

The fluid properties were identified in accordance with the prevailingtemperatures and so forth, in order to establish all pertinent fluidparameters. Under these conditions, the concentration of the aluminumion may be directly reflected in the electrical conductivity or sigma(σ) as identified on the y axis 154 of the graph 150.

Meanwhile, the concentration of the aluminum ion 65 or the donated ion65 from the anode 92 is equal to current divided by a constantrepresenting certain material properties characteristic of the materialof the anode 92. It is also divided by the volumetric mass flow rate. Ofcourse, the units must be consistent in order to maintain dimensionalconsistency throughout the equation. The result of that concentration isthat the electrical conductivity 154 is also proportional to thatconcentration. In fact, the change in concentration between the maximumconcentration in the system 10, and the maximum electrical conductivity154 at any point reflects ions removed from solution. Electricalconductivity is proportional to a constant times the concentration ofthe ion in question, aluminum in this example. Thus, the rise inelectrical conductivity is proportional to the rise in concentration ofaluminum ion, multiplied by that constant.

Stated another way, or in consequence thereof, the net electricalconductivity of a fluid having a constitution of ions therein is asummation of the individual electrical conductivities, where eachelectrical conductivity is proportional to a constant peculiar to thematerial, multiplied by the concentration of that material in the flow.In order to calibrate back to reality from this theoretical calculation,a parameter zeta (ζ). Values of zeta are typically in the range of fromabout 0.4 to about 0.7. The value of zeta is proportional toconcentration multiplied by a constant of proportionality (18.34 foraluminum) multiplied by the volumetric flow rate of water divided bycurrent and divided by the molecular weight of the species whoseconductivity and concentration are in question.

The foregoing relationship, when written in mathematical equation form,is the equation by which one may determine the initial set point 164 oroptimum 164 at which to operate the system 10.

The operational point 164 represents an optimum according to therepresentation that the precipitation efficiency, called zeta, is equalto the concentration of the ion in question multiplied by a constant ofproportionality (18.34 for aluminum) and multiplied by the volumetricflow rate of the incoming water 20 divided by the current and themolecular weight of the ion in question. Thus, this zeta (ζ) principallydefines the electrical conductivity 154 in the chart 150.

Operation above the point 168 is within a region 169 bounded by theboundary 167 above which excessive maintenance will be required.Excessive maintenance will be required because the system 10 willperiodically pass into the fouling region 172 identified by the point170, a zero value of the slope 162, the first derivative 162 of thecurve 160.

The boundary 171 defines the region 172 in which fouling will absolutelyoccur. Fouling occurs because the mass transfer limit 158 has been met,and the current is continuing to increase, thus creating ion speciesthat will precipitate and foul the anode 92. Meanwhile, to operate abovethe point 168, is to add current 152 within the excessive maintenanceregion 169. Operation is above the border 167 or boundary 167.Variations in temperature, fluid properties, constitution of the fluid20, and the like may result, and typically will therefore result, inperiodic excursions into the fouling region 172 from the point 168.

Thus, a set point 164 provides a certain amount of protection againstsuch excursions into the excessive maintenance region 169, the foulingregion 172, or both. Meanwhile, the marginal increase in electricalconductivity 154, and thus ions dissolve in solution, above the point164 has a diminishing return. Note the increase in current 152 betweenthe points 164 and 168. Note the difference in electrical conductivity154 between the points 164 and 168. The marginal increase in electricalconductivity 154 as a result of increases in current 152 is simply toomarginal to be worth the risk of excessive maintenance or fouling.

Likewise, however, the point 174 is operating at a lower current 152.This results in a lower electrical conductivity 154 reflecting fewerions in solution. The region 175 defined by the boundary 173 coincidentwith the point 174 represents excess capital cost. For example, too muchcapacity is being required as infrastructure, in the way of the iongenerator 12 specifically, and probably as well in the precipitationreactor 14. This excessive infrastructure is due to an unwillingness topush the current 152 above the value represented by the point 174.

Meanwhile, the marginal increase in electrical conductivity 154 byincreasing the current above the value corresponding to the point 174 issignificant. This represents little risk of passing into the foulingregion 172, and thus the region 175 is an excess capital region 175. Toomuch infrastructure is created without being effectively used. Withoutan undue amount of power expense, additional current may be deliveredfrom the current source 50 into each cell to achieve the increased ionconcentrations, reflected by the electrical conductivity 154, withoutundue increases in current 152.

The excessive power region 166 established by the boundary 165 reflectsthe fact that the point 164 achieves an optimal value of electricalconductivity 154 (ion concentration in solution) at a modest orreasonable input of current 152. Note that the slope 162 begins to dropoff substantially at values of current 152 above the point 164.

For example, above the point 168, almost no perceptible benefit inelectrical conductivity 154 is achieved, while a substantial increase incurrent 152 is required. Thus, the marginal value of power increasesbetween the points 168 and 170 clearly militates against operatinganywhere within that range. Meanwhile, the risks discussed hereinaboveare not worth operating above the point 168. On the other hand, theexcessive power region 166 suggests that more capacity can be built morecheaply than excessive power can be purchased.

This optimization may be done by comparing the economic value indistributed value of money over time, present value of expenditure, orsimply the advertised cost per barrel of water treated. Thus, when thecost-per-barrel of increased power in the excessive power region 166warrants, then the additional capital expenditure for adding cells maybe warranted.

In one embodiment, cells may be taken offline while in operation.Accordingly, automatically switching may simply provide for optimizingthe operation at the point 164 or thereabouts, within some toleranceregion. This may be done in order to maximize the value of powerpurchased for driving the current source 50, while still obtainingmaximum dissolved ions as represented by the electrical conductivity154. Thus, one may optimize economically to find the point 164 at whichthe economics of maintenance, power costs, and capital investment arebest balanced according to financial considerations or economics.

In certain embodiments, a sensitivity of the curve 160 to variations inflow rate, current, operational efficiency, and the like may result inthe curve 160 shifting. For example, the curve 160 may move in adirection 178 a if the mass transfer limit 158 or mass transport limit158 is reduced. Similarly, increases in the mass transfer limit 158 ormass transport limit 158 may result in the curve 160 moving higher atthe point 170 where contact is made.

Considered another way, a current limit 156 may be controlled byphysical phenomena such as electrical conductivity, area, currentdensity, and the like. Ultimately, the current limit 156 may depend on avariety of physical parameters and physical material properties. Thus, apoint of intersection 159 at which the current limit 156 intersects themass transport limit 158 may actually move upward or downward.Accordingly, the curve 160 may shift in a direction 178 a or a directionof 178 b as a result of the change of the mass transfer limit 158.

However, the directions 178 a, 178 b also represent the process ofoptimization. For example, the current limit 156 is a theoreticallimitation on the ability to drive current 152 through the anode 92 andinto the flow 130. Thus the discrepancy measured in the direction of thex axis 152 or the current axis 152 between the current limit 156 and thecurve 160 represents an inefficiency. That inefficiency is measurable asthe amount of current 152 that is effectively lost to ionizing the metalions 65. It is consumed in the thermodynamic losses incident to allactual physical processes.

For example, in accordance with the second law of thermodynamics, atheoretical limitation on how a process may occur is a matter of certainanalyses. Nevertheless, the realities of time, space, materialproperties, and various losses in processes result in some efficiencyless than the theoretical maximum. Thus, the current limit 156 may besimply calculated. However, it will typically never be achieved in anactual physical system. Rather, the curve 160 is qualitatively theactual relationship between conductivity 154 (which represents ions insolution) and the current 152 actually applied to an anode 92.

In optimizing performance, it is desired to move the curve 160 in adirection 178 b, toward the current limit 156, and the mass transportlimit 158. Any failure of the curve 160 to match the curves 156, 158represents inefficiency. That inefficiency represents the addition ofcurrent between the operational point 164 and the current limit 156. Theionization or electrical conductivity 154 lost is represented by thedistance between the point 164 of operation and the mass transfer limit158.

Optimization is desirable and possible in a system 10 in accordance withthe invention. The processes incident to EC documented in the prior artmay be represented by a depressed or reduced mass transport limit 158 aconsiderably below the original mass transfer limit 158 of a system 10.Accordingly, the resulting curve 160 a in prior art systems representsthe electrical conductivity in their quiescent fluids.

For example, prior art systems combine in a single reactor both theprocesses of ionization and precipitation. In fact, many combine theprocesses in the exact same physical space between electrode plates. Asa direct result, the curve 160 a is limited not only by the currentlimit 156, but also by the reduced mass transfer limit 158 a. Thedifference between the mass transport limit 158 a and the mass transportlimit 158 is a direct consequence of the quiescence of prior artsystems, compared to the vigorous, hyper-turbulent, high-Reynolds-numberflow in the lumen 96 of a cell 90 in accordance with the invention.

Consequences falling out of that quiescence include a point 170 a atwhich fouling begins if current 152 is increased. Thus, the decay in thecurve 160 a begins at the point 170 a at which the mass transport limit158 a limits any further ability to benefit from an increase in theavailable current 152 supplied. The curve 160 a is shifted to a muchlower curve and has a zero value of slope at a point 170 a representinga much lower current 152. It also has a higher fraction of that currentdevoted to losses as represented by the distance between the point 170 aand the current limit 156 along the mass transport limit 158 a.

One may note that the optimization of a curve 160 a is circumscribed bythe same current limit 156, but at a much lower value of current 152.Likewise, the curve 160 a is limited by the mass transport limit 158 aand is much reduced because of the lack of the hyper-turbulentconvection of plug flow in the cell 90 of a system 10 available with theinvention. Thus, the point of intersection 159 a at which the currentlimit 156 intersects the mass transport limit 158 a represents atheoretical optimum or maximum that the curve 160 a may fit.

However, the same thermodynamic limitations exist. Moreover, additionalelectrical losses occur due to the inefficiencies of ion generation.This is a direct result of the quiescence and the coexistence ofionization, precipitation, and flocculation in the same physical space.They act as retardants to both the process of ionization and the processof precipitation.

Referring to FIG. 6, a process 180 for controlling the operational point164 is illustrated. The process 180 involves not only an initialselection of an operating point 164, but also a sensitivity analysis. Asystem 10 may perturb the conditions about the point 164, in order todetermine whether it may be further improved or optimized.

Referring to FIG. 6, as a very real and practical matter, conditions forwaste water streams 20 being remediated are not in a steady statecondition. Waste water constitution (the catalog or list of constituentdissolve solids, salts, heavy metals, and so forth) may vary day to dayand hour to hour as waste water is delivered by tank, truck, train,pipeline, or the like to a system 10 in accordance with the invention.

Therefore, to maintain operation at currents 152 well below the excessmaintenance boundary 167 represented by the point 168, it is imperativethat a control mechanism be developed. In one embodiment of an apparatusand method in accordance with invention, a process 180 may be used forcontinuing monitoring and feedback control of the system 10 inaccordance with the invention.

Initially, determining 181 a metal concentration may involve selectionof a particular metal. Calculation of the total concentration will berequired in order to treat the particular constitution in a waste waterstream 20.

For example, the concentration of the candidate sacrificial anode metalrequired is equal to a level of current multiplied by the molecularweight of a constituent to be removed, divided by the constant relatingto the candidate metal (18.34 in the case of aluminum) also divided bythe volumetric flow rate through the system 10. This is all multipliedby the precipitation efficiency, zeta.

The system 10 may determine 181 the concentration expected in solutionof the flow 130 for each and every metal type to be removed from theflow 130 as described hereinabove. The summation of the requirements foreach metal to be scavenged or removed will result in the netconcentration required of the sacrificial metal ions 65 to beconstituted in the anode 92.

Next, determining 182 a maximum current 152, or the currentcorresponding to the operating point 164, involves additional equationsexpressing the relationship between the incoming waste water stream 20and its constitution, from the water analysis report. Also, the currentis a function of experimental data indicating operation of theoreticalequations as discussed herein, the concentration of the sacrificialmetal, and so forth.

One may note that the precipitation efficiency, zeta, is a rating factoror reality factor adjusting theoretical numbers. Thus, such empiricalinformation will reveal the value of zeta. In initial analyses, a valueof zeta within the range from about 0.4 to about 0.7 may be selected,and parametric variations may be run to establish the range of thevariables effecting the current 152 at the set point or operationalpoint 164.

Next, a system may be put in operation and the current 152 may be set ata value corresponding to the point 164 as determined from the step 182.Setting 183 the current 152 may be followed by starting 184 the system10 and running it to a steady state condition. The electricalconductivity 154 will be a constant without substantial variation for aparticular flow rate of a constitution involved with the water 20 beingremediated. Steady state simply means that the system has come to anoperating point 164 that is not varying substantially over time. As apractical matter, the conductivity at the outlet 38 of the precipitationreactor 14 should likewise be a constant. In other words, the system isoperating at a steady state.

Measuring 185 the electrical conductivity 154, at the inlet flow 30 intothe ion generator 12, as well as the maximum electrical conductivity 154at the outlet line 34 of the ion generator 12 will establish a point164. The pH adjuster 31 and flocculant polymer source 32 should notaffect the electrical conductivity 154.

Similarly, the electrical conductivity 154 at the outlet 38 of theprecipitation reactor 14 can also be measured. An effective electricalconductivity 154 change or delta (δ) will be the difference between theelectrical conductivity 154 in the outlet 38 from the precipitationreactor 14 less the initial electrical conductivity 154 at the inletline 30 to the ion generator 12.

Testing 186 determines whether the delta or change in electricalconductivity 154 is greater than zero. If so, then the operational point164 is to the left of the point 170 on the chart 150 of FIG. 5. If, forany reason, the change in electrical conductivity 154 is near zero ornegative, the system 10 should be shut down immediately and evaluatedagainst the water analysis report and the theoretical operating point164.

The reason for this is that a negative slope 162 on the curve 160indicates that operation has drifted into the fouling region 172. Thisis inappropriate, intolerable, and contrary to the design concept for asystem 10 in accordance with the invention.

Alternatively, a value of about zero, without a negative value mayindicate that no change in conductivity is occurring. Thus, no heavymetals are present to which to bond, and no heavy metals are present toalter conductivity. The presence of the sacrificial metal ions 65 is noteffective to remove non-present target metals. This indicates as ageneral proposition a change in the constitution of the influent 20.

A process 180 may include setting 187 a current at a high or incrementedvalue. This corresponds to moving current to the right from the point164 along the curve 160. Accordingly, some incremental increase incurrent 152 may be added to the current at the point 164, with aconsequent movement of the operational point 164 to the right along thecurve 160. This may be chosen as some fraction, such as a smallpercentage or small fraction on the order of five, ten, or fifteenpercent.

Typically, one desires to not perturb the current 152 beyond the point164 to approach a point 168. Definitely anathema is to pass the point170. This will not destroy the system, but will cause immediateincipience of fouling in the system. Fouling is difficult to recoverfrom, and an apparatus and method in accordance with the inventionshould effectively eradicate fouling. Thus, there is really nopercentage in operating under fouling conditions.

Next, measuring 188 the electrical conductivity 154 at the outlet 38reflects the electrical conductivity 154 on the curve 160. Thisindicates how far the point 164 has moved upward and to the right alongthe curve 160. Similarly, setting 189 the current 152 at a valuedeparting from the initial position of the point 164, downward to theleft, represents a negative increment or a decrement in the current 152.This may similarly be done as a proportion or fraction of the current152 at the point 164.

Measuring 190 the electrical conductivity 154 at this new value of thepoint 164 will result in a new slope 162, as well as a new value ofconductivity 154. Stated another way, both the value of conductivity154, and the rate of change of conductivity about the point 164, havenow been determined. Accordingly, an analysis 191 involves computing andcomparing the slope to the left of the initial point 164, to the slopeto the right. This will indicate where on the curve 160 the point 164 isrelative to such pivotal points as the point 174, the point 168, thepoint 170, and so forth.

Here, the change in electrical conductivity 154 may represent theperturbations about the point 164. The points 176 corresponds to anincrease in current 152, and the point 171 corresponds to a decrease incurrent 152. Thus, if the difference in electrical conductivity 154between the points 176 and 164 divided by or per the amount of change inthe current 152 therebetween, becomes negative, then operation istransferred into the fouling region 172.

Nevertheless, a value of difference in electrical conductivity 154 perdifference in current 152 may be represented as a fraction for the point176, and a different fraction for the point 177. If either of the slopes162 corresponding to either of the points 177, 176 is negative, then thesystem 10 is in the fouling region 172. It should be shut off, and theprocess 180 should be begun with new information and evaluation of thesystem 10. Meanwhile, the slopes 162 corresponding to the points 176 and177 should actually be decreasing in value with increased current 152.Thus, the curve 160 should be changing in slope, decreasing in slope,flattening out, and approaching the point 170.

In one embodiment, a fraction of the slope 162 of the current limit 156may be used. For example, if a slope 162 has decreased to less thanabout one third, then the tradeoff of electrical conductivity 154 forcurrent 152 is particularly poor. Stated another way, the marginal valueof an increase in current 152 is a very limited increase in electricalconductivity 154, and thus in the presence of additional ions 65. Aftera few tests, and a sensitivity analysis for different ranges ofconstituents in the incoming water 20, a specific fraction may beselected. The slope 162 should never be allowed to decline below thatfraction of the initial current limit 156. This depends very much on thesensitivity of the system 10 to the changes in temperature, fluidproperties, constitution of the incoming influent stream 20, and soforth.

Adjusting 192 current 152 for the point 164 may be thought of as afunction of the ratio of the slopes 162 corresponding to the points 176and 177. Likewise, the net change in the functional value, that is, theactual electrical conductivity 154, is also an independent variable onwhich the adjusted current 152 will depend. Typically, adjustment 192may be based on experiment, theory, or curve fits according to“numerical methods.” That term of art is well understood and defined inthe arts of mathematics and engineering modeling.

In one embodiment, a threshold minimum slope 162 may be established,even somewhat arbitrarily. For example, one third of the slope 162 ofthe current limit line 156 should be a reasonable proportion, based onthe principle of cosines. That is, most of the benefit to be achievedalong the curve 160 is achieved well before the point 170 of a zerovalue of slope 162.

A return 193 to continuing operation will typically involve a return 193to the step 184 of running the system 10 in a steady state. Periodicrepetition of the steps 184 through 192 will maintain the system 10sensitive to and responsive to changes in environment, constitution ofthe incoming water stream 20, and so forth. Meanwhile, the intrinsicmaterial properties or fluid properties such as viscosity, density, andso forth as they may be affected by temperature and constitution mayalso be factored into the sensitivity analysis of the method 180 orprocess 180.

Referring to FIG. 7, while continuing to refer generally to FIGS. 1through 10, a chart 194 or graph 194 illustrates an origin 195 at whicha distance axis 196 identified as x intersects a conductivity axis 198representing electrical conductivity 154. Electrical conductivity may bemeasured in micro Siemens per centimeter. Similarly, conductivity 154may be described in terms of inverse Ohms per unit distance. In thegraph 194, the data rise 199 represents an offset 199 between the origin195 and an initial value of electrical conductivity 154.

The point 202 represents a starting point 202 or an initial value 202 ofelectrical conductivity 198. Within the ion generator 12, the curve 203,which is linear, typically, progresses with an increase in distance 196along the length of a cell 90 of the ion generator 12 to a maximum value204.

In the illustrated embodiment, the electrical conductivity at the point204 is a function of the mass flow rate, the current, the type ofmaterial at the anode, as well as the constitution (e.g., the overallsuite of constituents within the incoming water 20), and so forth.

In fact, the data rise 199 reflects the electrical conductivity 154 ofan initial stream 20 passed into the ion generator 12 through the flow30. Thus, the electrical conductivity 198 at the point 202 reflects anynumber of constituents that may have an effect on electricalconductivity thereof. Thus, the rise in electrical conductivity 198between the points 202 and 204 represents the increase in electricalconductivity as a result of adding ions 65 from the sacrificial anode92. Thus, the linearity of the curve 203 is following the current limitcurve 156 of FIG. 5. A correspondence exists.

Nevertheless, as illustrated in FIG. 5, the curve 160 departs from thecurrent limit 156. Thus, the curve 203 may depart somewhat from an exactlinearity, or from a slope exactly consistent with the current limit156.

Nevertheless, the increase in electrical conductivity 198 between thepoints 202 and 204 is a direct function or has a direct variation withflow rate, current, and the length of the anode. Each of these directlyaffects, and thus is directly proportional to, the increase inelectrical conductivity 198 in traversing a curve 203 to the point 204.

The decay curves 205 a, 205 b, 205 c are simply instances of ageneralized decay curve 205. Thus, herein it is proper to speak of allthe curves 205, or any numbered item according to that referencenumeral. Meanwhile, a trailing letter simply means a specific instanceof the item corresponding to the reference numeral. Thus, it is properto illustrate, refer to, or designate using a trailing reference letteror to refer only to the generalized reference numeral.

The decay curves 205 a, 205 b, 205 c refer to different conditions thatdepend on the incoming water 20 to be treated. For example, the curve205 a represents clean water absent brine, such as sodium chloride, andwithout heavy metals. Accordingly, the rise in electrical conductivity198 to the point 204 is entirely due to the addition of the sacrificialanode ions 65. Meanwhile, the drop in electrical conductivity indicatesthat the heavy metal content has been eliminated by the ion generator 12and precipitation reactor 14. Thus, the value of the electricalconductivity drops to the lowest value, reflected by the point 206 a.

Similarly, the curve 205 b represents brine containing heavy metals.Accordingly, upon increase of the electrical conductivity 198 to thevalue at the point 204, the decay curve 205 b decreases the electricalconductivity 198 according to the removed heavy metals, and the removedsacrificial ions 65. This results in the electrical conductivity 198dropping to the point 206 b. Note that the point 206 b is still abovethe axis 196, indicating that residual electrical conductivity 198 isresulting from the brine, which has not been removed by the system 10.

The decay curve 205 c results in termination at a point 206 c, becausethe water 20 being treated is water having brine and no heavy metals.Accordingly, the rise in electrical conductivity from the point 202 tothe point 204 is entirely due to the donated metal ions 64 from theanode 92. Once those metal ions are removed, the decay curve 205 csettles back to the original value at the point 206 c, which reflectsthe presence of brine, and no heavy metals.

In general, the region between the curves 205 a and 205 c is theoperating envelope of the system 10. Thus, whether the water iscompletely clean of heavy metals, or laden with heavy metals, theseextrema are indicated by the graph 194.

It will be appreciated that conductivity (σ) is but one of conductivity,acidify (pH), and temperature (T) that can be ascertained at points 202,204, 206 such that an apparatus and method in accordance with theinvention may be similarly optimized and controlled.

Referring to FIGS. 8 and 9, the experimental work giving rise to thegraphs 150, 194 was validated by comparing predicted to actualexperimental performance of a system 10 in accordance with theinvention. For example, each of the charts 210 includes an x axis 212 orhorizontal axis 212 representing a change in electrical conductivity aspredicted. That change in electrical conductivity is the value ofelectrical conductivity at a point 206 compared to electricalconductivity at a point 202.

Each of the values is represented as a logarithm of the actual measuredvalue. Thus, each of the charts 210 represents a log-log comparison.Thus, the y axis 214 or vertical axis 214 represents the change inelectrical conductivity actually measured in the experimental system 10.

The curves 216 represents a leased squares fit of the data. The median218 is illustrated by a dashed line. The individual data points 220 ofindividual experiments are distributed in the graphs 210. Thecorrelation quality is evident from the “Pvalue” indicated by the letterp in each case, that ratio is less than four significant figures behindthe decimal point. Thus, the “Pvalue” is less than one ten thousandth.This represents a high degree of statistical significance to thecorrelation.

The r squared value indicating the degree of correlation is indicated bythe expression RSq and has a value of 0.95 in the first series of tests,and a value of 1.87 in the second series of tests. Similarly, the rootmean square of the error represented by the moniker RMSE is alsoillustrated.

Thus the charts 210 of FIGS. 8 and 9 evidence that the physical system10 illustrated in FIGS. 1 through 4 indeed operates according to thequalitative representations of FIGS. 5 and 7. Nevertheless, the specificvalues of any particular curve 160, 200 will depend upon the specificconstitution of the incoming water 20, the value of current 50, thematerial properties of the fluids, the flow rate, and so forth asdescribed hereinabove.

Referring to FIG. 10, while continuing to refer generally to FIGS. 1through 10, in one embodiment of a cell 90 in accordance with theinvention, a specific embodiment of a sacrificial anode 92 may beencased within a tube 94 representing a cathode 94. In the illustratedembodiment, a cap 222 may be formed to include a sleeve 223. The sleeve223 will engage with a seal 236 and otherwise secure mechanically to thetube 94. Any suitable mechanism will operate.

Various seals 236, such as ‘O’ rings 236 or the like may be used to sealindividual surfaces from passing any fluids, such as vapors, liquids, orthe like therethrough. In certain embodiments, a washer 238 may act as acompression fitting 238 activated or distorted by the tube 94 as it fitswithin the sleeve 225 of the cap 222. In this embodiment, an axial loadalong the axial direction of the anode 92 may be enforced between thewall of the tube 94, and the washer 238. Thus, the washer will distortin an axial direction, shrinking in that direction in response to forceor stress. Meanwhile, the washer 238 will expand in a radial directionin direct consequence thereof according to the Poisson effect, whichrepresents a conservation of mass in solidus materials.

A feed pipe 240 may be secured, such as by welding to feed the flow 30into the annulus 96 within the tube 94. An anchor 242 may be securedagainst a surface 243 such as by threading. In one embodiment, a lug 244held by the anchor 242 against the surface 243 of the tube 94 will feedpower from a power line 246 or power cable 246 connected to the currentsource 50. Various switching and control mechanisms may intervene inorder to control application of current, control flow direction into thefeed pipe or port 240 and so forth.

The anode 92 may be positioned by guides 248. In the illustratedexample, guides 248 are positioned near the top end of the anode 92, andnear the bottom end thereof. Typically, the guides 248 may be spoked orincludes spokes 250 that represent radial supports 250 positioning theanode 92. The guide 248 may include an outer rim 251 and inner rim 252.

Each of the spokes 250 may extend along a length or axial direction andpresent a vane 253 that tends to rotate or spin the flow within theannulus 96. In this way, additional turbulence may be initiated in thelumen 96 or annulus 96. The lower guide 248 may be similarly situated,but may also be adapted to act as a seat 248 for the lower end of theanode 92.

For example, in the illustrated embodiment, the anode 92 may be taperedto a reduced diameter and fitted into a seat 248 in order to beself-piloting. The spokes 250 and their vanes 253 may simply beintegrated. For example, a face 253 of a spoke 250 may extend radially,axially, and twist circumferentially in order to induce spinning in theflow. It may assure that the flow 130 passes through or between thespokes 250, and has sufficient cross-sectional area and hydraulicdiameter to maintain the flow velocity, volumetric flow rate, and soforth. Reductions of area that may be occasioned by the interference byspokes 250 will simply increase velocity, and turbulence.

In the illustrated embodiment, a load block 256 may be a right circularcylinder, which may or may not include spokes 250 and intervening spacesto promote flow therethrough. In the illustrated embodiment, the flow130 passes through the blocks 256, which support the lower guide 248axially. Ultimately, the flow 130 will pass through the guide 248 andthe load block 256 that stands the guide 248 off away from the outletport 258 or outlet line 258. It provides sufficient cross-sectional areaand hydraulic diameter. Hydraulic diameters is a term of art definedmathematically in engineering science as four times the cross-sectionalarea divided by the wetted perimeter of a conduit of any shape orpassage of any shape.

In accordance with the operational approach for the cells 90, additionalvariations in diameter, effective roughness, trip lines, or the like maybe added to the interior of the tube 94, such as along the surface 95.In order to assure turbulent flow immediately. Typically, flows developover a distance. Accordingly, boundary layer theory predicts theestablishment of flows. In order to maximize turbulence, roughness,features that may trip, such as projections, ridges, and the like, aswell as the spokes 250, the vanes 253, integral thereto, or the like maybe added to the surface 95, in order to quickly develop turbulence and abulk plug flow 130 within the annulus 96.

The present invention may be embodied in other specific forms withoutdeparting from its purposes, functions, structures, or operationalcharacteristics. The described embodiments are to be considered in allrespects only as illustrative, and not restrictive. The scope of theinvention is, therefore, indicated by the appended claims, rather thanby the foregoing description. All changes which come within the meaningand range of equivalency of the claims are to be embraced within theirscope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. An apparatus operable to remediate a flow of liquid, theapparatus comprising: a cathode defining, and extending in, an axialdirection; an anode, as an ion generator, spaced in a radial directionfrom the cathode and formed of a sacrificial metal as a source ofsacrificial ions of the sacrificial metal when placed in a flow ofliquid containing target ions to be removed from the liquid by thesacrificial ions; a conduit, defined by and between the cathode andanode, and sized to conduct the sacrificial ions in the flow of liquidin a hyper-turbulent condition, selected to resist by shear forces in aisolating boundary layer an agglomeration of reaction products of thetarget ions and sacrificial ions proximate the anode, past the cathodeand anode at a Reynolds number having a value an order of magnitudegreater than a maximum value thereof corresponding to laminar flow; afirst sensor, detecting a first value of an input parametercharacterizing the flow upstream from the anode and cathode; a secondsensor, detecting a second value of the input parameter characterizingthe flow downstream from the cathode and anode; and a controller,operably connected to control a generation rate of the sacrificial ionsby controlling a current of electrons passing between the anode andcathode, based on a difference between the first and second values. 2.The apparatus of claim 1, wherein the conduit is sized and shaped tocreate the isolating, hydrodynamic, boundary layer in the flow, therebyisolating the target ions from the anode.
 3. The apparatus of claim 2,wherein the target ions are metal ions.
 4. The apparatus of claim 1,wherein the cathode and anode are spaced apart radially.
 5. Theapparatus of claim 1, wherein the conduit is an annulus extending in theaxial direction.
 6. The apparatus of claim 1, wherein the cathode,anode, and conduit are each axially symmetric.
 7. The apparatus of claim1, wherein the target ions are a contaminant in the flow.
 8. Theapparatus of claim 1, wherein the conduit, anode, and cathode are sizedand shaped to resist agglomeration of the target ions under weak forcestherebetween by maintaining the flow hyper-turbulent continually in theaxial direction.
 9. The apparatus of claim 1, further comprising: andthe current source providing electrical current between the cathode andthe anode; a controller controlling the current source.
 10. Theapparatus of claim 1, wherein the conduit is sized and shaped to resistformation of precipitants containing the target ions within the iongenerator by maintaining hydrodynamic shear forces effective to overcomeforces of agglomeration between reacted ones of the sacrificial ions andtarget ions at the anode.
 11. An apparatus operable to remediate a flowof liquid, the apparatus comprising: an electrochemical reactor systemcomprising a generator, of an ion generation type having a first volume,and a precipitator, having a second volume, the first and second volumesbeing separate and distinct from one another; a source of a flow, theflow comprising a liquid containing a target ion to be removed from theflow, the source operably connected to pass the flow to the generator; afirst sensor, operably connected to measure an input parametercharacterizing a property of the flow, upstream from the generator; thegenerator, comprising a cathode and an anode, the anode connected toprovide an anodic ion in the first volume, the first volume being sizedand shaped to resist agglomeration of reaction products formed betweenthe anodic ion and the target ion by shear forces in a laminar boundarylayer maintained between the anode and the flow maintained in ahyper-turbulent condition in the first volume; a second sensor, operablyconnected and capable of measuring an output parameter characterizingthe property downstream from the generator; and a controller operablyconnected to control a generation rate of the anodic ion by controllinga current of electrons passing between the anode and cathode, based on adifference between the output parameter and the input parameter.
 12. Theapparatus of claim 11, wherein the precipitator is sized, shaped, andoperably connected to receive the flow downstream from the generator andconduct the flow in a laminar flow condition.
 13. The apparatus of claim12, wherein the size and shape of the second volume are selected toprovide a first dwell time of the flow therethrough effective to reactthe anodic ion and the target ion.
 14. The apparatus of claim 13,comprising a clarifier downstream from the precipitator effective toprovide a second dwell time of the flow therethrough effective toagglomerate reaction products formed between the anodic ion and thetarget ion.
 15. The apparatus of claim 11, wherein the first volume issized and shaped to separate therewithin most of the population of theanodic ion generated at the anode from most of the population of thetarget ion in the flow by the laminar boundary layer.
 16. The apparatusof claim 11, wherein the property is selected from a mass flow rate,volume flow rate, temperature, density, pH, total dissolved solids,total suspended solids, electrical conductivity, a concentration of athe target ion in the flow, degree of clarification, and pressure,corresponding to the flow.
 17. The apparatus of claim 16, comprising apump operably connected to the generator to control fluid properties ofthe flow including at least one of the mass flow rate, volume flow rate,temperature, concentration of a target ion, and pressure.
 18. Theapparatus of claim 17, comprising: a current source operably connectedto provide the current in response to the controller; the controller,effective to adjust the current to a level effectively eliminatingfouling of the anode; a pH adjuster upstream from the precipitator; aflocculant source upstream from the precipitator; and clarifierdownstream from the precipitator, the clarifier effective to removeflocculated reaction products formed between the target ion and theanodic ion in the flow.
 19. An apparatus for remediating a flow ofliquid, operable as a system configured as a reactor of anelectrochemical type operating on a flow of liquid containing targetions to be removed from the flow, the apparatus comprising: a pump toprovide a flow and controlling at least one of head (pressure),velocity, mass flow rate, volumetric flow rate, and turbulence in theflow; a generator of an ion generator type, having a generator inletoperably connected to the pump and defining a first volume containing ananode and a cathode; a current source operably connected to urge anodicions into the flow by providing a current of electrons passing betweenthe anode and the cathode; the pump, sized to provide plug flow in ahyper-turbulent condition through the generator along the length of theanode at all times during operation thereof; a precipitator operablyconnected to, and downstream from, the generator and defining a secondvolume separate and distinct from the first volume; a sensor systemoperably connected to detect a parameter characterizing at least one ofa flow condition, a characteristic of the liquid, and a constituent ofthe flow; a controller operably connected to the current source tocontrol the number of anodic ions in the flow by altering the currentbased on a difference between a first value of the parameter, detectedupstream from the generator, and a second value of the parameter,detected downstream from the generator.
 20. The system of claim 19,wherein: the second value is detected downstream from the precipitator;the parameter is selected from a mass flow rate, volume flow rate,temperature, density, pH, total dissolved solids, total suspendedsolids, turbidity, electrical conductivity, concentrations ofconstituents of the flow, degree of clarification, and pressure,corresponding to the flow; and the constituent is selected from thetarget ion, the anodic ion, a material lighter than the liquid, and amaterial heavier than the liquid.